Questions tagged [digital-communications]
Related to all communication systems that use a given digital sequence as an interface between the source and the channel input.
365
questions
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37 views
Need help in computing the evolution of symbol error rate for uncoded OOK scheme over fading channels
I am trying to reproduce the results exhibited in Fig. 1. in the reference, i.e., "Error performance of coded FSO links in turbulent atmosphere modeled by gamma-gamma distributions" linked to (https://...
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1answer
54 views
Can anybody explain to me how to solve such questions? Constellation Diagram [closed]
i'm not able to proceed with such questions. If someone could explain how to solve such questions, would be a big help. Thanks.
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0answers
34 views
Connecting an industrial PLC to Android phone over a wire
Building an Android app that will take a picture and based on pixel values determine whether to continue operation or not (output true or false) to the PLC.
It is a Mitsubishi FX3U-48 PLC and I don'...
0
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0answers
48 views
GBE (Gigabit Ethernet) Magnetic Coils Connection Order
I am designing a MEZ PCB and I need to connect the GBE coils to the assigned pins of single board computer's MEZ connector. My trouble is I do not want to use any more via for this connections. Hence, ...
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2answers
59 views
Preventing audio feedback in an underwater multiway intercom
I'm trying to transmit data(bytes) from a speaker (out) to microphone (in) via an FM modulated link. Now I have the problem that both will be used simultaneously (full duplex) and next to each other (...
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2answers
78 views
Is there a method to get the carrier from the recieved QPSK signal?
If we have given a signal and we know that is a modulated QPSK signal, can we recover the carrier if we know the carrier frequency fc.
Edit: A clarification, I do not have to do it in hardware, a ...
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0answers
18 views
How to perform multiplication at the time series level for chirp signals
As the title said: How to perform multiplication at the time series level for chirp signals?
In LoRa modulation, when received a chirp modulated signal, to demodulate it, LoRa will first multiple the ...
25
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13answers
4k views
Examples of fluid (including air) being used to transmit digital data? [closed]
We usually use electrons to communicate data across wires, and sometimes we use light also. Does anyone know of real world example systems that use fluids (including air) to do this, and the ...
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1answer
41 views
What is the transmission bandwidth for a BASK (Binary Amplitude Shift Keying) signal?
What is the transmission bandwidth for a BASK (Binary Amplitude Shift Keying) signal?
Shouldn't it be infinity as short periods of sinusoids are used to depict 1 and 0 to depict 0?
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0answers
23 views
CAN Transciever kbps to Hz at TXD Pin
I am new to the CAN Bus and have designed an application example. The Transceiver I have chosen is TJA1044Gx.
The transceiver data sheet says :
I want to know if I have only Transceiver, Analog ...
0
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2answers
69 views
Can we band pass filter QPSK signal?
Consider we have QPSK signal with carrier frequency 10kHz. Generally, we demodulate or use matched filter on the the QPSK signal and recover the transmitted bit or the symbols. If the QPSk signal is ...
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0answers
7 views
How is n_pucch_2 in rrc layer computed
In LTE network I know that n_pucch_2 is used to indicate the resource index for pucch format 2/2a/2b. And I know its value is defined in higher layer. But how is the value computed and defined in the ...
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1answer
39 views
What is the minimum sampling rate for QPSK or what is the bandwidth of QPSK signal?
Consider we have created a QPSK signal with a carrier frequency 100kHz. Before applying matched filter or demodulation we need to take sampls from the received signal. So what is the minimum sampling ...
0
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1answer
31 views
Machine comms troubleshooting
While this may be suited for an automotive section I believe my question is better suited to this forum.
I'm having OBD II comms issues and have a run a similar troubleshooting process to what's ...
0
votes
1answer
49 views
JSON for GSM Comm on STM32
I am making a remote monitoring system using STM32F1 MCU in which there are few digital and analog sensors attached and I would send their readings to a remote server periodically. Can I use JSON ...
3
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0answers
137 views
Strange I2C communication
I am currently trying to test the SHT3x series humidity sensors by Senserion. I have their EK-H4 evaluation kit to get data from the sensors. I can plug in the sesnsors provided with the kit, and all ...
0
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2answers
38 views
1-wire differentiate read from write
I've been reading documentation on 1-wire and I think I'm having a brainfart. How does the slave differentiate a read slot from a write slot?
reference:
https://www.maximintegrated.com/en/app-notes/...
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0answers
89 views
How to Low-Pass PDM Output Data
I have a PDM-Mems Microphone which provides me with 101010 data, the Microphone has a Clock of 3Mhz. I read the manual about how PDM is generated, but I haven't worked with digital filters yet and in ...
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1answer
29 views
Pairing vs Master-slave between BT Module to BT Module
If I take two identical BT modules, for example HC05 or HC06 then is it possible to pair the two modules with each other or is it like you need 1 master and 1 slave module for pairing?
Edit:
Now I ...
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1answer
68 views
Bluetooth vs BT Beacon [closed]
While trying to understand how BT devices work I came across another related term "BT Beacon". Is it same as BT communication or if a device is termed as BT beacon then it would have some specific ...
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0answers
48 views
What is the fieldbus for Unitronics PLC?
I am currently investigating the inner behavior of a PLC of the brand Unitronics. I identified several bus for the communication with actuators, other PLCs, etc (like Modbus or CANbus)
One thing I ...
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0answers
10 views
finding the minimal length of a broadcasting frame in a channel(CSMA/CD)
i am unsure about this question. would appreciate your assistance with it.
in the following CSMA/CD network with cable length L and propagation T. assuming that the signal is not decreasing and there'...
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2answers
69 views
Does direct GPIO communication between 2 microcontrollers requires pull up/down
If I want to use GPIO pins of two microcontrolles as a mean of simple communication (e.g. reporting an event by sending 1 or 0), Do I need to enable internal pull up or pull down resistors on any of ...
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0answers
80 views
Probing LPC bus with an FPGA yields gibberish — wiring problem?
I'm trying to repeat the TPM key dumping experiment by Pulse Security using a motherboard with Secure Boot and the same TPM1.2 chip onboard, equipped with Windows 8.
However, when I connect the FPGA ...
0
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1answer
58 views
Finding the overhead and distance of an unknown code based on message making algorithm
for an information word M with m bits that is coded as following:
M is coded into a word A using an unknown code that allows detection of not more than one error.
the code word is the word obtained ...
0
votes
1answer
15 views
loading multiple shift registers from few pins
We want to load two 32 bit data shift registers without concatenating them using 4 control lines (SI1, SI2 clock, latch). It can be done by bit banging but can it be done using SPIs using only 4 lines?...
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0answers
23 views
Find Bit Error Rate and Eb/N0?
I have read about Bit Error Rate and Eb/N0 to find out how can I generate them. I understand BER but what confused me is Eb/N0. How can I find Eb/N0 values and the corresponding BER values.
I have ...
1
vote
1answer
65 views
Signal placement in flat ribbon cable, FPC or FFC with digital and power signals
I want to interface different boards with FPC/FFC or ribbon cable and I was wondering about the placement of the signals in the cable.
I plan to have a 39 signals FPC with :
1 SPI bus (SCK, MOSI, ...
0
votes
1answer
53 views
Visualise a bit pattern
My objective is to send a bit pattern of 1000 bits from one microcontroller (PIC or Atmel) to another one using the SPI method.
How can I visualize the bit pattern so I can find the errors of ...
1
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1answer
37 views
Source generator for Satellite Tuner input
I need to design a source generator for a TV factory. They want to automatize the functional tests by applying a test module to the TV's at the end of the production line. All the peripherals of the ...
1
vote
1answer
43 views
What is the effect of redundancy coding on the bit error rate?
If I have a channel with bit error rate BER = \$10^{-3}\$ after modulation, but this is too high so I decide to add repetition coding. With 2 code words and block length of 3 such that I have a ...
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3answers
90 views
Choosing best bus and protocol for ~128 clients over the wire
I am up to design system with ~128 MCUs communicating to one MCU master. Communication will be bidirectional. Data will be mostly sensor reads, but I plan to use the bus also as communication method ...
0
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1answer
106 views
How do I stop signal looping with I/O port in this communication system
I am still a student. When I am designing communication system I am facing this problem: As shown in the figure I need to communicate with Master and Slave. But Master and Slave have single I/O port ...
2
votes
3answers
138 views
How is companding different from pre-emphasis and de-emphasis?
What I know is that interference increases linearly with frequency and thus noise power is concentrated at higher frequency. So, to reduce noise, pre-emphasis and de-emphasis filters are used which ...
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votes
1answer
272 views
Signed and unsigned numbers in verilog
I understand the concept of fixed point and multiplying signed with unsigned by sign extension the unsigned number with 1 bit of '0' so it will be signed always positive number, But my question
If I ...
0
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1answer
92 views
UART Transmit issue in VHDL
I'm working on a UART transmit process (uart_transmit) in VHDL (115200 baud, 8 data bits, 1 stop bit and no parity). I need the transmit line ...
0
votes
1answer
166 views
Are horizontal and vertical back porches required for digital video, and if so, why?
The necessity of vertical and horizontal front and back porches in analog video seem fairly intuitive to me, but why are they necessary for digital video at all? In this LCD module data sheet and this ...
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1answer
87 views
In wireless communication, what is “channel length”?
In wireless communication, I am confused about what people are referring to when they use the term 'channel length.' Can someone explain the term or provide me a definition?
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64 views
High data rate (~1-5 Mpbs) Point to Point Radio
I'm working on a rocket project at my University, and am trying to find a point to point / point to multipoint radio capable of a hopefully 1-5 Mbps data rate between a ground station a directional ...
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2answers
150 views
What device can convert (EEG) voltage data to real voltage? [closed]
I seek a device that can be programmed to output physical voltages based on a set of datapoints. For example:
...
0
votes
1answer
51 views
Inverse Z-transform Problem [closed]
I'm rather stuck trying to compute the inverse Z-transform y[n] of the function below. I'm having trouble selecting the correct formulas from the table to achieve the right solution.
Any help with ...
1
vote
1answer
86 views
Ringing issue on I2C FM+ bus between MCU and few sensors - Power supply issue?
I'm experiencing some issues while probing a problematic I2C bus on the oscilloscope.
We want to interface several TLV493D-A1B6, with a STM32L4 (we are working as well on STM32F4 and have the same ...
0
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3answers
55 views
Practical Limitations to 1-Wire Communication Speed [closed]
What are some practical limitations to the speed of a 1-Wire interface?
1
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2answers
160 views
Can someone explain the use of the transistor in this circuit?
I came across a schematic which implemented a 1 Wire interface. However, this 1-Wire interface circuit also includes a transistor connected as shown in the picture. Can somebody expain why this has ...
0
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5answers
160 views
RS485 IC Termination Resistor Configuration
I've made a mistake on a design, that went into production...
It was built like the drawing on the left, with R702 to 5V and R703 to GND, it should have been backwards... like the drawing on the ...
1
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0answers
58 views
Derivation of stability criterion for type 3 digital PLL
Could anyone help to derive the following expression (4.23) which is the stability criterion for type 3 digital PLL ?
Note: Screenshots are taken from Floyd Gardner's book : Phaselock Techniques 3rd ...
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votes
1answer
31 views
What are cost-effective and ways of providing global communication between two devices besides internet and SMS?
I am currently in the process of building a system which allows vehicles to send information back and forth with an Arduino. The main problem I am facing right now, is that the current implementation ...
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2answers
57 views
Geometric representation of GMSK signal
Can anyone provide me the geometric representation of GMSK signal? Also, am I correct in saying that bit energy of GMSK is same as its symbol energy since MSK is a binary modulation scheme with only ...
0
votes
1answer
56 views
Printer Data Cables with *suspected* IC boards [duplicate]
I've one found of those printer data cables that have some kind of pair integrated circuit along them, one at each end just before the plugs, I was wondering if there is a less invasive way of ...
0
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1answer
145 views
Asynchronous FIFO in clock domain crossing
Clock domain crossing issue can be solved by using asynchronus FIFO with input frequency f1 is of the source domain and f2 is of the destination frequency.
If the data is sent in bursts, depth can be ...
